Allow output plugin to round-robin between hosts

[Zemmy01]

This is intended for when data is being written to a Telegraf instance instead of an InfluxDB instance.
When using Telegraf it would be useful to be able to load balance and provide fault tolerance.

Currently with only one host being allowed a separate instance is required for each Telegraf instance.
Instead of just being able to provide multiple hosts to the output plugin.

As an example, please view the below diagrams. In this case each process is designed to be deployed in it's own docker container.

Without round-robin capabilities:

With round-robin capabilities:

If this is already available in some form then please let me know, as currently I can find no documentation to support this.